AUTHOR=Inês Carla , Parra-Lobato Maria C. , Paredes Miguel A. , Labrador Juana , Gallardo Mercedes , Saucedo-García Mariana , Gavilanes-Ruiz Marina , Gomez-Jimenez Maria C. 

TITLE=Sphingolipid Distribution, Content and Gene Expression during Olive-Fruit Development and Ripening

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.00028

DOI=10.3389/fpls.2018.00028

ISSN=1664-462X

ABSTRACT=<p>Plant sphingolipids are involved in the building of the matrix of cell membranes and in signaling pathways of physiological processes and environmental responses. However, information regarding their role in fruit development and ripening, a plant-specific process, is unknown. The present study seeks to determine whether and, if so, how sphingolipids are involved in fleshy-fruit development and ripening in an oil-crop species such as olive (<italic>Olea europaea</italic> L. cv. Picual). Here, in the plasma-membranes of live protoplasts, we used fluorescence to examine various specific lipophilic stains in sphingolipid-enriched regions and investigated the composition of the sphingolipid long-chain bases (LCBs) as well as the expression patterns of sphingolipid-related genes, <italic>OeSPT</italic>, <italic>OeSPHK</italic>, <italic>OeACER</italic>, and <italic>OeGlcCerase</italic>, during olive-fruit development and ripening. The results demonstrate increased sphingolipid content and vesicle trafficking in olive-fruit protoplasts at the onset of ripening. Moreover, the concentration of LCB [t18:1(8<italic>Z</italic>), t18:1 (8<italic>E</italic>), t18:0, d18:2 (4<italic>E</italic>/8<italic>Z</italic>), d18:2 (4<italic>E</italic>/8<italic>E</italic>), d18:1(4<italic>E</italic>), and 1,4-anhydro-t18:1(8<italic>E</italic>)] increases during fruit development to reach a maximum at the onset of ripening, although these molecular species decreased during fruit ripening. On the other hand, <italic>OeSPT</italic>, <italic>OeSPHK</italic>, and <italic>OeGlcCerase</italic> were expressed differentially during fruit development and ripening, whereas <italic>OeACER</italic> gene expression was detected only at the fully ripe stage. The results provide novel data about sphingolipid distribution, content, and biosynthesis/turnover gene transcripts during fleshy-fruit ripening, indicating that all are highly regulated in a developmental manner.</p>